cis-olefins are an important source of pharmacological and biological compounds such as pheromones. Unfortunately, the synthesis of cis-olefins is a very difficult and expensive process because of the tendency of the beginning reaction products to isomerize into inactive or inhibitory trans-isomers. An example of a simple cis-olefin which has proven difficult to produce economically is cis-9-tricosene (Z-9-tricosene).
cis-9-tricosene is a known pheromone and is an important attractant used to control flies in cattle and poultry production. In order to make this compound readily available for use in insect control a variety of chemical syntheses have been developed. These syntheses involve (1) classical types of organic syntheses utilizing alkynes, phosphonium salts, ketone reductions with hydrazine (Huang-Minlon type reductions), ozonolysis of 1,5-cyclooctadiene, sulfone coupling, or borane coupling, (2) syntheses utilizing metathesis chemistry, (3) syntheses using electrochemical coupling of carboxylic acids, and (4) syntheses utilizing Grignard coupling of various erucyl and oleyl derivatives with the appropriate Grignard reagents. More recent syntheses involve (1) coupling of 1-bromo-2-phenylthioethenes with Grignard reagents in the presence of palladium or nickel catalysts, (2) reductions of certain dialkylated tosylmethyl isocyanides, (3) catalytic ring-opening of dihydropyran by certain Grignard reagents, and (4) condensation of certain Grignard reagents with the appropriate aldehydes to produce alcohols that can be dehydrated to give a mixture of alkenes containing the tricosene product.
Many of the more classical syntheses require the use of alkynes or Wittig reagents to obtain the desired cis-stereochemistry present in the housefly pheromone. Although these reagents produce cis-9-tricosene in high purity, their use in large scale production of pure cis-9-tricosene is prohibitively expensive. Currently, the most economical synthesis of cis-9-tricosene is achieved by coupling oleyl bromide with N-amylmagnesium bromide in tetrahydrofuran at 0.degree. C.-5.degree. C. using lithium chlorocyanocuprate, which is toxic.
Thus, it would be a significant contribution to the art to develop an alternative chemical synthesis for cis-olefins such as cis-9-tricosene which utilizes economical, less toxic reagents.
It would also be advantageous if the alternate process for the synthesis of cis-olefins were simple, and were characterized by easy to scale-up reactions which did not require multiple reaction vessels.
It would additionally be advantageous if the process for the synthesis of cis-olefins did not require the isolation or purification of intermediates between chemical synthesis steps.
It is an object of this invention to provide an economical, less toxic process for the synthesis of cis-olefins.
It is also an object of this invention to provide a simple, easy to scale-up process for the synthesis of cis-olefins which does not require multiple reaction vessels.
It is a further object of this invention to provide a process for the synthesis of cis-olefins which does not require the isolation or purification of the intermediates produced in the reaction.
It is a further object of this invention to provide a process for the synthesis of cis-9-tricosene.
Other aspects, objects, and several advantages of this invention will be apparent from the foregoing specifications, example, and claims.